Many plant species such as citrus trees and the like are subject to root rot disease and similar diseases. To combat this problem as well as provide trees of desired characteristics, a seedling of the tree in question has grafted to it a bud from a clone having disease immunity characteristics and growth characteristics which, if the same can be properly rooted, would solve the problem in that trees could be grown with the desired disease immunity and/or growth characteristics. Many problems, however, are encountered in attempting to root the root stock resulting from a graft, particularly in those instances where the plant species under consideration can be classified as difficult-to-root in the first place.
Conventional practice sometimes involves girdling the wood stock grown from the bud grafted to an initial seedling. This girdling involves scraping away part of the bark of the root stock and tightly surrounding the removed area with a wire or other physical restricting device which cuts off the flow of nutrients to the basic seedling from which the root stock is grown. It is hoped in this process to promote rooting of the root stock itself by the formation of roots above the girdling wire while simultaneously killing off the basic seedling and thus finally providing a plant having desired characteristics.
In almost all instances, the foregoing procedure of girdling has resulted in failure of the root stock itself to eventually take root and the problem of efficiently providing plants immune to certain diseases up to the time of the present invention still existed.